Frost line depth in Yadkin County, NC
How deep the ground freezes in Yadkin County, NC
14 in. Dig to 14 in, just below the frost. Nearest NOAA station: Yadkinville 6 E, 6.8 mi.
Your building department sets the legal frost line depth (IRC Table R301.2(1)); footings must go below it (R403.1.4.1). Call them before you dig.